1. Field of the Invention
This invention is directed to devices and methods for cleaning gas and for muffling a gas discharge. In one particular aspect it is directed to cleaning and muffling the gas discharged from a gas-powered valve actuator for a valve on a natural gas pipeline. It is also directed to devices and methods which permit the environmentally safe re-use of actuator lubrication oil and the recovery of other materials which previously have been discharged into the environment.
2. Description of Related Art
Natural gas pipelines use gas-powered valve actuators to operate the valves used to control the flow of the natural gas. Pipeline valves may be either quarter turn, such as a plug or ball type, or may be a sliding gate. With both, a positive means such as a gas-powered actuator is highly desirable. The pressure of the gas within the pipeline (sometimes pressure regulated) is used as a power source for the valve actuator, especially in remote locations. The actuators can be motor-powered or cylinder (vane or piston) type. Sometimes a gas/hydraulic system is used in which gas is directed into a tank containing hydraulic oil and then to a cylinder. A typical gas-operated valve actuator is disclosed in my U.S. Pat. No. 4,380,325.
Motor-powered actuators use a line lubricator to add lubricating oil to the power gas. This oil lubricates the moving parts of the motor and the seals of the control valves. This oil commingles with the exhausting gas and is exhausted to the environment adjacent the actuator. The gas/hydraulic system cylinder actuators exhaust an amount of oil from the intermixing of gas and oil. This amount increases as the seals wear. Cylinder actuators, other than the gas/hydraulic type, use a line lubricator that adds lubricant to the power gas. This oil is contained in the exhaust gas.
The typical one-to-two minute discharge of a mist of lubricating oil into the atmosphere is harmful to the environment. Of even more importance, some pipeline systems have become contaminated with PCB via lubricating oils used in apparatuses such as compressors. These can be discharged along With the actuator lubricating oils. At some locations an odorizer is added to the pipeline gas. If such an actuator exhausts gas with an odor, it can cause the needless Concern of a malfunction or of pipeline damage.
The noise level of gas motor powered actuators has been measured at levels exceeding above 110 decibels. A noise level of below 85 decibels is considered acceptable.
Exhaust gas from actuators concentrated in one location, e.g. at plants such as compressor stations, has been manifolded together and directed to a central scrubber/separator. This practice is only possible when the restriction of the actuator exhaust does not adversely affect the power output of the actuator. At locations where manifolding is not possible, or for those actuators which cannot function with a restricted exhaust, no known scrubber or muffler device has been applied.
Lubricators for valve actuators require periodic filling and maintenance. It is not uncommon during maintenance procedures for there to be some spillage of the lubricating oil.
The prior art discloses a great variety of gas cleaning apparatuses and filters. For example, Perry Equipment Corporation provides a Mighty-Mic FG 372 A Filter Element for ultra fine filtration which removes 98% of particles 0.5 microns and larger with an overall removal of 99.95%.
In accordance with 37 C.F.R. .sctn.1.56, the following are disclosed:
"Mighty-Mic (FG-372-A) Filter Element," 1983, describing a gas filter.
"Line Break-ESD Systems, Inc.," 1989, describing valve actuators. This company is co-owned with the present application.
"Limitorque High Pressure Gas Powered Valve Operators," 1983, Limitorque Corporation.
"Type G Brochure High Pressure Gas Actuator," 1989, EIM Company, Inc.
"Shafer Valve Operating Systems," 1980, Shafer Valve Co.
U.S. Pat. No. 4,380,325 discloses a valve actuator.
There has long been a need for efficient, effective, and safe devices and methods for exhausting gas and gas commingled with harmful materials from valve actuators. There has long been a need for a sound reducer for muffling the high level sound of an operating valve actuator exhaust. There has long been a need for devices and methods for recovering oil and other materials from such an exhaust. There has long been a need for devices and methods for re-using such recovered oil.